ATMOSPHERIC SULFUR AND ITS LINKS TO THE BIOTA 



171 



1968 



Ljusnan 



1969 



(e) 



1970 



Fig. 4 The pH changes in rivers and lakes in Sweden. The four upper curves 

 are for rivers and lake outlets in southern Sweden. The fifth curve is for the 

 Ljusnan River in central Sweden and shows the effect of washout of acid 

 water every year following spring melting. From Engstrom.' 9 



